1.. _todo: 2 3========= 4TODO list 5========= 6 7This section contains a list of smaller janitorial tasks in the kernel DRM 8graphics subsystem useful as newbie projects. Or for slow rainy days. 9 10Difficulty 11---------- 12 13To make it easier task are categorized into different levels: 14 15Starter: Good tasks to get started with the DRM subsystem. 16 17Intermediate: Tasks which need some experience with working in the DRM 18subsystem, or some specific GPU/display graphics knowledge. For debugging issue 19it's good to have the relevant hardware (or a virtual driver set up) available 20for testing. 21 22Advanced: Tricky tasks that need fairly good understanding of the DRM subsystem 23and graphics topics. Generally need the relevant hardware for development and 24testing. 25 26Expert: Only attempt these if you've successfully completed some tricky 27refactorings already and are an expert in the specific area 28 29Subsystem-wide refactorings 30=========================== 31 32Remove custom dumb_map_offset implementations 33--------------------------------------------- 34 35All GEM based drivers should be using drm_gem_create_mmap_offset() instead. 36Audit each individual driver, make sure it'll work with the generic 37implementation (there's lots of outdated locking leftovers in various 38implementations), and then remove it. 39 40Contact: Daniel Vetter, respective driver maintainers 41 42Level: Intermediate 43 44Convert existing KMS drivers to atomic modesetting 45-------------------------------------------------- 46 473.19 has the atomic modeset interfaces and helpers, so drivers can now be 48converted over. Modern compositors like Wayland or Surfaceflinger on Android 49really want an atomic modeset interface, so this is all about the bright 50future. 51 52There is a conversion guide for atomic and all you need is a GPU for a 53non-converted driver (again virtual HW drivers for KVM are still all 54suitable). 55 56As part of this drivers also need to convert to universal plane (which means 57exposing primary & cursor as proper plane objects). But that's much easier to 58do by directly using the new atomic helper driver callbacks. 59 60Contact: Daniel Vetter, respective driver maintainers 61 62Level: Advanced 63 64Clean up the clipped coordination confusion around planes 65--------------------------------------------------------- 66 67We have a helper to get this right with drm_plane_helper_check_update(), but 68it's not consistently used. This should be fixed, preferrably in the atomic 69helpers (and drivers then moved over to clipped coordinates). Probably the 70helper should also be moved from drm_plane_helper.c to the atomic helpers, to 71avoid confusion - the other helpers in that file are all deprecated legacy 72helpers. 73 74Contact: Ville Syrjälä, Daniel Vetter, driver maintainers 75 76Level: Advanced 77 78Improve plane atomic_check helpers 79---------------------------------- 80 81Aside from the clipped coordinates right above there's a few suboptimal things 82with the current helpers: 83 84- drm_plane_helper_funcs->atomic_check gets called for enabled or disabled 85 planes. At best this seems to confuse drivers, worst it means they blow up 86 when the plane is disabled without the CRTC. The only special handling is 87 resetting values in the plane state structures, which instead should be moved 88 into the drm_plane_funcs->atomic_duplicate_state functions. 89 90- Once that's done, helpers could stop calling ->atomic_check for disabled 91 planes. 92 93- Then we could go through all the drivers and remove the more-or-less confused 94 checks for plane_state->fb and plane_state->crtc. 95 96Contact: Daniel Vetter 97 98Level: Advanced 99 100Convert early atomic drivers to async commit helpers 101---------------------------------------------------- 102 103For the first year the atomic modeset helpers didn't support asynchronous / 104nonblocking commits, and every driver had to hand-roll them. This is fixed 105now, but there's still a pile of existing drivers that easily could be 106converted over to the new infrastructure. 107 108One issue with the helpers is that they require that drivers handle completion 109events for atomic commits correctly. But fixing these bugs is good anyway. 110 111Somewhat related is the legacy_cursor_update hack, which should be replaced with 112the new atomic_async_check/commit functionality in the helpers in drivers that 113still look at that flag. 114 115Contact: Daniel Vetter, respective driver maintainers 116 117Level: Advanced 118 119Fallout from atomic KMS 120----------------------- 121 122``drm_atomic_helper.c`` provides a batch of functions which implement legacy 123IOCTLs on top of the new atomic driver interface. Which is really nice for 124gradual conversion of drivers, but unfortunately the semantic mismatches are 125a bit too severe. So there's some follow-up work to adjust the function 126interfaces to fix these issues: 127 128* atomic needs the lock acquire context. At the moment that's passed around 129 implicitly with some horrible hacks, and it's also allocate with 130 ``GFP_NOFAIL`` behind the scenes. All legacy paths need to start allocating 131 the acquire context explicitly on stack and then also pass it down into 132 drivers explicitly so that the legacy-on-atomic functions can use them. 133 134 Except for some driver code this is done. This task should be finished by 135 adding WARN_ON(!drm_drv_uses_atomic_modeset) in drm_modeset_lock_all(). 136 137* A bunch of the vtable hooks are now in the wrong place: DRM has a split 138 between core vfunc tables (named ``drm_foo_funcs``), which are used to 139 implement the userspace ABI. And then there's the optional hooks for the 140 helper libraries (name ``drm_foo_helper_funcs``), which are purely for 141 internal use. Some of these hooks should be move from ``_funcs`` to 142 ``_helper_funcs`` since they are not part of the core ABI. There's a 143 ``FIXME`` comment in the kerneldoc for each such case in ``drm_crtc.h``. 144 145Contact: Daniel Vetter 146 147Level: Intermediate 148 149Get rid of dev->struct_mutex from GEM drivers 150--------------------------------------------- 151 152``dev->struct_mutex`` is the Big DRM Lock from legacy days and infested 153everything. Nowadays in modern drivers the only bit where it's mandatory is 154serializing GEM buffer object destruction. Which unfortunately means drivers 155have to keep track of that lock and either call ``unreference`` or 156``unreference_locked`` depending upon context. 157 158Core GEM doesn't have a need for ``struct_mutex`` any more since kernel 4.8, 159and there's a GEM object ``free`` callback for any drivers which are 160entirely ``struct_mutex`` free. 161 162For drivers that need ``struct_mutex`` it should be replaced with a driver- 163private lock. The tricky part is the BO free functions, since those can't 164reliably take that lock any more. Instead state needs to be protected with 165suitable subordinate locks or some cleanup work pushed to a worker thread. For 166performance-critical drivers it might also be better to go with a more 167fine-grained per-buffer object and per-context lockings scheme. Currently only 168the ``msm`` and `i915` drivers use ``struct_mutex``. 169 170Contact: Daniel Vetter, respective driver maintainers 171 172Level: Advanced 173 174Move Buffer Object Locking to dma_resv_lock() 175--------------------------------------------- 176 177Many drivers have their own per-object locking scheme, usually using 178mutex_lock(). This causes all kinds of trouble for buffer sharing, since 179depending which driver is the exporter and importer, the locking hierarchy is 180reversed. 181 182To solve this we need one standard per-object locking mechanism, which is 183dma_resv_lock(). This lock needs to be called as the outermost lock, with all 184other driver specific per-object locks removed. The problem is tha rolling out 185the actual change to the locking contract is a flag day, due to struct dma_buf 186buffer sharing. 187 188Level: Expert 189 190Convert logging to drm_* functions with drm_device paramater 191------------------------------------------------------------ 192 193For drivers which could have multiple instances, it is necessary to 194differentiate between which is which in the logs. Since DRM_INFO/WARN/ERROR 195don't do this, drivers used dev_info/warn/err to make this differentiation. We 196now have drm_* variants of the drm print functions, so we can start to convert 197those drivers back to using drm-formatted specific log messages. 198 199Before you start this conversion please contact the relevant maintainers to make 200sure your work will be merged - not everyone agrees that the DRM dmesg macros 201are better. 202 203Contact: Sean Paul, Maintainer of the driver you plan to convert 204 205Level: Starter 206 207Convert drivers to use simple modeset suspend/resume 208---------------------------------------------------- 209 210Most drivers (except i915 and nouveau) that use 211drm_atomic_helper_suspend/resume() can probably be converted to use 212drm_mode_config_helper_suspend/resume(). Also there's still open-coded version 213of the atomic suspend/resume code in older atomic modeset drivers. 214 215Contact: Maintainer of the driver you plan to convert 216 217Level: Intermediate 218 219Convert drivers to use drm_fbdev_generic_setup() 220------------------------------------------------ 221 222Most drivers can use drm_fbdev_generic_setup(). Driver have to implement 223atomic modesetting and GEM vmap support. Historically, generic fbdev emulation 224expected the framebuffer in system memory or system-like memory. By employing 225struct iosys_map, drivers with frambuffers in I/O memory can be supported 226as well. 227 228Contact: Maintainer of the driver you plan to convert 229 230Level: Intermediate 231 232Reimplement functions in drm_fbdev_fb_ops without fbdev 233------------------------------------------------------- 234 235A number of callback functions in drm_fbdev_fb_ops could benefit from 236being rewritten without dependencies on the fbdev module. Some of the 237helpers could further benefit from using struct iosys_map instead of 238raw pointers. 239 240Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter 241 242Level: Advanced 243 244Benchmark and optimize blitting and format-conversion function 245-------------------------------------------------------------- 246 247Drawing to dispay memory quickly is crucial for many applications' 248performance. 249 250On at least x86-64, sys_imageblit() is significantly slower than 251cfb_imageblit(), even though both use the same blitting algorithm and 252the latter is written for I/O memory. It turns out that cfb_imageblit() 253uses movl instructions, while sys_imageblit apparently does not. This 254seems to be a problem with gcc's optimizer. DRM's format-conversion 255helpers might be subject to similar issues. 256 257Benchmark and optimize fbdev's sys_() helpers and DRM's format-conversion 258helpers. In cases that can be further optimized, maybe implement a different 259algorithm. For micro-optimizations, use movl/movq instructions explicitly. 260That might possibly require architecture-specific helpers (e.g., storel() 261storeq()). 262 263Contact: Thomas Zimmermann <tzimmermann@suse.de> 264 265Level: Intermediate 266 267drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup 268----------------------------------------------------------------- 269 270A lot more drivers could be switched over to the drm_gem_framebuffer helpers. 271Various hold-ups: 272 273- Need to switch over to the generic dirty tracking code using 274 drm_atomic_helper_dirtyfb first (e.g. qxl). 275 276- Need to switch to drm_fbdev_generic_setup(), otherwise a lot of the custom fb 277 setup code can't be deleted. 278 279- Many drivers wrap drm_gem_fb_create() only to check for valid formats. For 280 atomic drivers we could check for valid formats by calling 281 drm_plane_check_pixel_format() against all planes, and pass if any plane 282 supports the format. For non-atomic that's not possible since like the format 283 list for the primary plane is fake and we'd therefor reject valid formats. 284 285- Many drivers subclass drm_framebuffer, we'd need a embedding compatible 286 version of the varios drm_gem_fb_create functions. Maybe called 287 drm_gem_fb_create/_with_dirty/_with_funcs as needed. 288 289Contact: Daniel Vetter 290 291Level: Intermediate 292 293Generic fbdev defio support 294--------------------------- 295 296The defio support code in the fbdev core has some very specific requirements, 297which means drivers need to have a special framebuffer for fbdev. The main 298issue is that it uses some fields in struct page itself, which breaks shmem 299gem objects (and other things). To support defio, affected drivers require 300the use of a shadow buffer, which may add CPU and memory overhead. 301 302Possible solution would be to write our own defio mmap code in the drm fbdev 303emulation. It would need to fully wrap the existing mmap ops, forwarding 304everything after it has done the write-protect/mkwrite trickery: 305 306- In the drm_fbdev_fb_mmap helper, if we need defio, change the 307 default page prots to write-protected with something like this:: 308 309 vma->vm_page_prot = pgprot_wrprotect(vma->vm_page_prot); 310 311- Set the mkwrite and fsync callbacks with similar implementions to the core 312 fbdev defio stuff. These should all work on plain ptes, they don't actually 313 require a struct page. uff. These should all work on plain ptes, they don't 314 actually require a struct page. 315 316- Track the dirty pages in a separate structure (bitfield with one bit per page 317 should work) to avoid clobbering struct page. 318 319Might be good to also have some igt testcases for this. 320 321Contact: Daniel Vetter, Noralf Tronnes 322 323Level: Advanced 324 325struct drm_gem_object_funcs 326--------------------------- 327 328GEM objects can now have a function table instead of having the callbacks on the 329DRM driver struct. This is now the preferred way. Callbacks in drivers have been 330converted, except for struct drm_driver.gem_prime_mmap. 331 332Level: Intermediate 333 334Rename CMA helpers to DMA helpers 335--------------------------------- 336 337CMA (standing for contiguous memory allocator) is really a bit an accident of 338what these were used for first, a much better name would be DMA helpers. In the 339text these should even be called coherent DMA memory helpers (so maybe CDM, but 340no one knows what that means) since underneath they just use dma_alloc_coherent. 341 342Contact: Laurent Pinchart, Daniel Vetter 343 344Level: Intermediate (mostly because it is a huge tasks without good partial 345milestones, not technically itself that challenging) 346 347connector register/unregister fixes 348----------------------------------- 349 350- For most connectors it's a no-op to call drm_connector_register/unregister 351 directly from driver code, drm_dev_register/unregister take care of this 352 already. We can remove all of them. 353 354- For dp drivers it's a bit more a mess, since we need the connector to be 355 registered when calling drm_dp_aux_register. Fix this by instead calling 356 drm_dp_aux_init, and moving the actual registering into a late_register 357 callback as recommended in the kerneldoc. 358 359Level: Intermediate 360 361Remove load/unload callbacks from all non-DRIVER_LEGACY drivers 362--------------------------------------------------------------- 363 364The load/unload callbacks in struct &drm_driver are very much midlayers, plus 365for historical reasons they get the ordering wrong (and we can't fix that) 366between setting up the &drm_driver structure and calling drm_dev_register(). 367 368- Rework drivers to no longer use the load/unload callbacks, directly coding the 369 load/unload sequence into the driver's probe function. 370 371- Once all non-DRIVER_LEGACY drivers are converted, disallow the load/unload 372 callbacks for all modern drivers. 373 374Contact: Daniel Vetter 375 376Level: Intermediate 377 378Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi 379--------------------------------------------------------------- 380 381Once EDID is parsed, the monitor HDMI support information is available through 382drm_display_info.is_hdmi. Many drivers still call drm_detect_hdmi_monitor() to 383retrieve the same information, which is less efficient. 384 385Audit each individual driver calling drm_detect_hdmi_monitor() and switch to 386drm_display_info.is_hdmi if applicable. 387 388Contact: Laurent Pinchart, respective driver maintainers 389 390Level: Intermediate 391 392Consolidate custom driver modeset properties 393-------------------------------------------- 394 395Before atomic modeset took place, many drivers where creating their own 396properties. Among other things, atomic brought the requirement that custom, 397driver specific properties should not be used. 398 399For this task, we aim to introduce core helpers or reuse the existing ones 400if available: 401 402A quick, unconfirmed, examples list. 403 404Introduce core helpers: 405- audio (amdgpu, intel, gma500, radeon) 406- brightness, contrast, etc (armada, nouveau) - overlay only (?) 407- broadcast rgb (gma500, intel) 408- colorkey (armada, nouveau, rcar) - overlay only (?) 409- dither (amdgpu, nouveau, radeon) - varies across drivers 410- underscan family (amdgpu, radeon, nouveau) 411 412Already in core: 413- colorspace (sti) 414- tv format names, enhancements (gma500, intel) 415- tv overscan, margins, etc. (gma500, intel) 416- zorder (omapdrm) - same as zpos (?) 417 418 419Contact: Emil Velikov, respective driver maintainers 420 421Level: Intermediate 422 423Use struct iosys_map throughout codebase 424---------------------------------------- 425 426Pointers to shared device memory are stored in struct iosys_map. Each 427instance knows whether it refers to system or I/O memory. Most of the DRM-wide 428interface have been converted to use struct iosys_map, but implementations 429often still use raw pointers. 430 431The task is to use struct iosys_map where it makes sense. 432 433* Memory managers should use struct iosys_map for dma-buf-imported buffers. 434* TTM might benefit from using struct iosys_map internally. 435* Framebuffer copying and blitting helpers should operate on struct iosys_map. 436 437Contact: Thomas Zimmermann <tzimmermann@suse.de>, Christian König, Daniel Vetter 438 439Level: Intermediate 440 441Review all drivers for setting struct drm_mode_config.{max_width,max_height} correctly 442-------------------------------------------------------------------------------------- 443 444The values in struct drm_mode_config.{max_width,max_height} describe the 445maximum supported framebuffer size. It's the virtual screen size, but many 446drivers treat it like limitations of the physical resolution. 447 448The maximum width depends on the hardware's maximum scanline pitch. The 449maximum height depends on the amount of addressable video memory. Review all 450drivers to initialize the fields to the correct values. 451 452Contact: Thomas Zimmermann <tzimmermann@suse.de> 453 454Level: Intermediate 455 456Request memory regions in all drivers 457------------------------------------- 458 459Go through all drivers and add code to request the memory regions that the 460driver uses. This requires adding calls to request_mem_region(), 461pci_request_region() or similar functions. Use helpers for managed cleanup 462where possible. 463 464Drivers are pretty bad at doing this and there used to be conflicts among 465DRM and fbdev drivers. Still, it's the correct thing to do. 466 467Contact: Thomas Zimmermann <tzimmermann@suse.de> 468 469Level: Starter 470 471 472Core refactorings 473================= 474 475Make panic handling work 476------------------------ 477 478This is a really varied tasks with lots of little bits and pieces: 479 480* The panic path can't be tested currently, leading to constant breaking. The 481 main issue here is that panics can be triggered from hardirq contexts and 482 hence all panic related callback can run in hardirq context. It would be 483 awesome if we could test at least the fbdev helper code and driver code by 484 e.g. trigger calls through drm debugfs files. hardirq context could be 485 achieved by using an IPI to the local processor. 486 487* There's a massive confusion of different panic handlers. DRM fbdev emulation 488 helpers had their own (long removed), but on top of that the fbcon code itself 489 also has one. We need to make sure that they stop fighting over each other. 490 This is worked around by checking ``oops_in_progress`` at various entry points 491 into the DRM fbdev emulation helpers. A much cleaner approach here would be to 492 switch fbcon to the `threaded printk support 493 <https://lwn.net/Articles/800946/>`_. 494 495* ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and 496 isn't a full solution for panic paths. We need to make sure that it only 497 returns true if there's a panic going on for real, and fix up all the 498 fallout. 499 500* The panic handler must never sleep, which also means it can't ever 501 ``mutex_lock()``. Also it can't grab any other lock unconditionally, not 502 even spinlocks (because NMI and hardirq can panic too). We need to either 503 make sure to not call such paths, or trylock everything. Really tricky. 504 505* A clean solution would be an entirely separate panic output support in KMS, 506 bypassing the current fbcon support. See `[PATCH v2 0/3] drm: Add panic handling 507 <https://lore.kernel.org/dri-devel/20190311174218.51899-1-noralf@tronnes.org/>`_. 508 509* Encoding the actual oops and preceding dmesg in a QR might help with the 510 dread "important stuff scrolled away" problem. See `[RFC][PATCH] Oops messages 511 transfer using QR codes 512 <https://lore.kernel.org/lkml/1446217392-11981-1-git-send-email-alexandru.murtaza@intel.com/>`_ 513 for some example code that could be reused. 514 515Contact: Daniel Vetter 516 517Level: Advanced 518 519Clean up the debugfs support 520---------------------------- 521 522There's a bunch of issues with it: 523 524- The drm_info_list ->show() function doesn't even bother to cast to the drm 525 structure for you. This is lazy. 526 527- We probably want to have some support for debugfs files on crtc/connectors and 528 maybe other kms objects directly in core. There's even drm_print support in 529 the funcs for these objects to dump kms state, so it's all there. And then the 530 ->show() functions should obviously give you a pointer to the right object. 531 532- The drm_info_list stuff is centered on drm_minor instead of drm_device. For 533 anything we want to print drm_device (or maybe drm_file) is the right thing. 534 535- The drm_driver->debugfs_init hooks we have is just an artifact of the old 536 midlayered load sequence. DRM debugfs should work more like sysfs, where you 537 can create properties/files for an object anytime you want, and the core 538 takes care of publishing/unpuplishing all the files at register/unregister 539 time. Drivers shouldn't need to worry about these technicalities, and fixing 540 this (together with the drm_minor->drm_device move) would allow us to remove 541 debugfs_init. 542 543Previous RFC that hasn't landed yet: https://lore.kernel.org/dri-devel/20200513114130.28641-2-wambui.karugax@gmail.com/ 544 545Contact: Daniel Vetter 546 547Level: Intermediate 548 549Object lifetime fixes 550--------------------- 551 552There's two related issues here 553 554- Cleanup up the various ->destroy callbacks, which often are all the same 555 simple code. 556 557- Lots of drivers erroneously allocate DRM modeset objects using devm_kzalloc, 558 which results in use-after free issues on driver unload. This can be serious 559 trouble even for drivers for hardware integrated on the SoC due to 560 EPROBE_DEFERRED backoff. 561 562Both these problems can be solved by switching over to drmm_kzalloc(), and the 563various convenience wrappers provided, e.g. drmm_crtc_alloc_with_planes(), 564drmm_universal_plane_alloc(), ... and so on. 565 566Contact: Daniel Vetter 567 568Level: Intermediate 569 570Remove automatic page mapping from dma-buf importing 571---------------------------------------------------- 572 573When importing dma-bufs, the dma-buf and PRIME frameworks automatically map 574imported pages into the importer's DMA area. drm_gem_prime_fd_to_handle() and 575drm_gem_prime_handle_to_fd() require that importers call dma_buf_attach() 576even if they never do actual device DMA, but only CPU access through 577dma_buf_vmap(). This is a problem for USB devices, which do not support DMA 578operations. 579 580To fix the issue, automatic page mappings should be removed from the 581buffer-sharing code. Fixing this is a bit more involved, since the import/export 582cache is also tied to &drm_gem_object.import_attach. Meanwhile we paper over 583this problem for USB devices by fishing out the USB host controller device, as 584long as that supports DMA. Otherwise importing can still needlessly fail. 585 586Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter 587 588Level: Advanced 589 590 591Better Testing 592============== 593 594Add unit tests using the Kernel Unit Testing (KUnit) framework 595-------------------------------------------------------------- 596 597The `KUnit <https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html>`_ 598provides a common framework for unit tests within the Linux kernel. Having a 599test suite would allow to identify regressions earlier. 600 601A good candidate for the first unit tests are the format-conversion helpers in 602``drm_format_helper.c``. 603 604Contact: Javier Martinez Canillas <javierm@redhat.com> 605 606Level: Intermediate 607 608Enable trinity for DRM 609---------------------- 610 611And fix up the fallout. Should be really interesting ... 612 613Level: Advanced 614 615Make KMS tests in i-g-t generic 616------------------------------- 617 618The i915 driver team maintains an extensive testsuite for the i915 DRM driver, 619including tons of testcases for corner-cases in the modesetting API. It would 620be awesome if those tests (at least the ones not relying on Intel-specific GEM 621features) could be made to run on any KMS driver. 622 623Basic work to run i-g-t tests on non-i915 is done, what's now missing is mass- 624converting things over. For modeset tests we also first need a bit of 625infrastructure to use dumb buffers for untiled buffers, to be able to run all 626the non-i915 specific modeset tests. 627 628Level: Advanced 629 630Extend virtual test driver (VKMS) 631--------------------------------- 632 633See the documentation of :ref:`VKMS <vkms>` for more details. This is an ideal 634internship task, since it only requires a virtual machine and can be sized to 635fit the available time. 636 637Level: See details 638 639Backlight Refactoring 640--------------------- 641 642Backlight drivers have a triple enable/disable state, which is a bit overkill. 643Plan to fix this: 644 6451. Roll out backlight_enable() and backlight_disable() helpers everywhere. This 646 has started already. 6472. In all, only look at one of the three status bits set by the above helpers. 6483. Remove the other two status bits. 649 650Contact: Daniel Vetter 651 652Level: Intermediate 653 654Driver Specific 655=============== 656 657AMD DC Display Driver 658--------------------- 659 660AMD DC is the display driver for AMD devices starting with Vega. There has been 661a bunch of progress cleaning it up but there's still plenty of work to be done. 662 663See drivers/gpu/drm/amd/display/TODO for tasks. 664 665Contact: Harry Wentland, Alex Deucher 666 667vmwgfx: Replace hashtable with Linux' implementation 668---------------------------------------------------- 669 670The vmwgfx driver uses its own hashtable implementation. Replace the 671code with Linux' implementation and update the callers. It's mostly a 672refactoring task, but the interfaces are different. 673 674Contact: Zack Rusin, Thomas Zimmermann <tzimmermann@suse.de> 675 676Level: Intermediate 677 678Bootsplash 679========== 680 681There is support in place now for writing internal DRM clients making it 682possible to pick up the bootsplash work that was rejected because it was written 683for fbdev. 684 685- [v6,8/8] drm/client: Hack: Add bootsplash example 686 https://patchwork.freedesktop.org/patch/306579/ 687 688- [RFC PATCH v2 00/13] Kernel based bootsplash 689 https://lore.kernel.org/r/20171213194755.3409-1-mstaudt@suse.de 690 691Contact: Sam Ravnborg 692 693Level: Advanced 694 695Outside DRM 696=========== 697 698Convert fbdev drivers to DRM 699---------------------------- 700 701There are plenty of fbdev drivers for older hardware. Some hardware has 702become obsolete, but some still provides good(-enough) framebuffers. The 703drivers that are still useful should be converted to DRM and afterwards 704removed from fbdev. 705 706Very simple fbdev drivers can best be converted by starting with a new 707DRM driver. Simple KMS helpers and SHMEM should be able to handle any 708existing hardware. The new driver's call-back functions are filled from 709existing fbdev code. 710 711More complex fbdev drivers can be refactored step-by-step into a DRM 712driver with the help of the DRM fbconv helpers. [1] These helpers provide 713the transition layer between the DRM core infrastructure and the fbdev 714driver interface. Create a new DRM driver on top of the fbconv helpers, 715copy over the fbdev driver, and hook it up to the DRM code. Examples for 716several fbdev drivers are available at [1] and a tutorial of this process 717available at [2]. The result is a primitive DRM driver that can run X11 718and Weston. 719 720 - [1] https://gitlab.freedesktop.org/tzimmermann/linux/tree/fbconv 721 - [2] https://gitlab.freedesktop.org/tzimmermann/linux/blob/fbconv/drivers/gpu/drm/drm_fbconv_helper.c 722 723Contact: Thomas Zimmermann <tzimmermann@suse.de> 724 725Level: Advanced 726